What this tool is for
Write a selected print-density value—72, 96, 150, or 300 DPI—into a JPG. This changes print metadata, not the number of pixels or the real detail in the image.
How to use it
- Choose an image up to 50MB.
- Select 72, 96, 150, or 300 DPI.
- Select Process Image to create a JPG with the chosen JFIF density metadata.
- Download it and verify the print settings in the application that will use it.
What happens to your image
GuavaPix re-encodes the visible pixels as JPEG and writes the selected density into the JFIF header when available. The operation is local and does not add pixels.
Practical uses
- Set 300 DPI metadata for a print-layout workflow.
- Change a JPG's declared density for desktop-publishing software.
- Prepare an image for a system that checks DPI metadata.
- Compare print-size interpretation at different densities.
DPI is not pixel resolution
A 3000 × 2400 pixel image has the same pixels whether tagged 72 or 300 DPI. At 300 DPI it is interpreted as roughly 10 × 8 inches for print; at 150 DPI, roughly 20 × 16 inches. Resampling pixels is a separate operation.
Important limitations
- Changing DPI does not increase sharpness or pixel count.
- The output is JPEG, so transparency is removed.
- Some applications ignore or reinterpret density metadata.
- Professional print workflows may require color-profile controls this tool does not provide.
Frequently asked questions
Does 300 DPI make an image higher quality?
No. It changes the declared print density. Real detail comes from sufficient pixel dimensions.
What DPI should I choose?
Use the value required by the destination. 300 DPI is common for quality print, while screens are usually governed by pixel dimensions.
Why did my print size change?
Print applications divide pixel dimensions by DPI to estimate physical size.
Does the tool resize pixels?
No. It keeps the decoded pixel dimensions and updates density metadata in the JPEG output.